We expect ~1000 hits a day combined (and very modest spikes expected) and consequent bandwidth use of 20gb per month.

So, I ask for:

latest versions of PHP, Python on a popular distro, accessible via shell

fair pricing at this traffic level (~10$ per month)

fair pricing for scaling up and good upgrade/scale options

GUI config for multiple sites/ server features

sync via SSH even over an obscure network architecture (I am told we have no "public IPs")

As a hypothetical question, which provider could help me set up a GIT/Mercurial+TRAC server the most easily? (I know there are things like Bitbucket but this seems a hypothetical challenge that corelates well)

I heard good things about WebFaction and Pyrox. How will they suit my above requirements? I dont want to steer the conversation prematurely.

I will start off from WebFaction or VPSlink which have been doing it for years, and the economics are firmly on that side and also easier for a newb. But Linode is what I choose a great upgrade for a serious site.

As Mike Keller has said Linode is a good choice, they are reliable and cheap (starting ~$20US). You can choose from many Linux distros and install all applications you need. I've got one, and I have php, python, apache, subversion+trac, etc. If you need your provider to install software for you then you're asking for managed servers, that cost money so if you want to keep it cheap you have to do it yourself otherwise you have to pay.
If you need GUI for configuring your sites you can install Webmin on your server, it has a lot of features, you can manage configuration of DNS, Apache, FTP, etc. If you need MySQL GUI management then install PHPMyAdmin.